Preprints
Filtering by Subject: Physical Sciences and Mathematics
The effect of lateral variations in Earth structure on Last Interglacial sea level
Published: 2021-07-12
Subjects: Physical Sciences and Mathematics
It is generally agreed that the Last Interglacial (LIG; 130 – 115 ka)was a time when global average temperatures and global mean sea level were higher than they are today. However, the exact timing, magnitude, and spatial pattern of ice melt is much debated. One difficulty in extracting past global mean sea level from local observations is that their elevations need to be corrected for glacial [...]
Energetics and mixing of stratified, rotating flow over abyssal hills
Published: 2021-07-12
Subjects: Earth Sciences, Oceanography, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics
One of the proposed mechanisms for energy loss in the ocean is through dissipation of internal waves, in particular above rough topography where internal lee waves are generated. Rates of dissipation and diapycnal mixing are often estimated using linear theory and a constant value for mixing efficiency. However, previous oceanographic measurements found that non-linear dynamics may be important [...]
A convolutional neural network approach to estimate earthquake kinematic parameters from back-projection images
Published: 2021-07-09
Subjects: Physical Sciences and Mathematics
The retrieval of earthquake finite-fault kinematic parameters after the occurrence of an earthquake is a crucial task in observational seismology. Routinely-used source inversion techniques are challenged by limited data coverage and computational effort, and are subject to a variety of assumptions and constraints that restrict the range of possible solutions. Back-projection (BP) imaging [...]
The origin and 3D architecture of a km-scale deep-water scour-fill: example from the Skoorsteenberg Fm., Karoo Basin, South Africa
Published: 2021-07-08
Subjects: Physical Sciences and Mathematics
Scours, and scour fields, are common features on the modern seafloor of deep-marine systems, particularly downstream of submarine channels, and in channel-lobe-transitions-zones. High-resolution images of the seafloor have improved the documentation of the large scale, coalescence, and distribution of these scours in deep-marine systems. However, their scale and high aspect ratio mean they can be [...]
Impact of igneous intrusion and associated ground deformation on the stratigraphic record
Published: 2021-07-08
Subjects: Physical Sciences and Mathematics
The geomorphology and sediment systems of volcanic areas can be influenced by uplift (forced folding) related to subsurface migration and accumulation of magma. Seismic geomorphological analysis presents a unique tool to study how surface morphology and subsurface magma dynamics relate, given seismic reflection data can image buried landscapes and underlying intrusions in 3D at resolutions of [...]
Channel incision into a submarine landslide: an exhumed Carboniferous example from the Paganzo Basin, San Juan, Argentina
Published: 2021-07-08
Subjects: Physical Sciences and Mathematics
Emplacement of submarine landslides, or mass transport deposits, can radically reshape the physiography of continental margins, and strongly influence subsequent sedimentary processes and dispersal patterns. The irregular relief they generate creates obstacles that force reorganisation of sediment transport systems. Subsurface and seabed examples show that channels can incise directly into [...]
Melting temperature changes during slip across subglacial cavities drive basal mass exchange
Published: 2021-07-07
Subjects: Earth Sciences, Glaciology, Physical Sciences and Mathematics
The importance of glacier sliding has motivated a rich literature describing the thermomechanical interactions between ice, liquid water, and bed materials. Early recognition of the gradient in melting temperature across small bed obstacles led to focussed studies of regelation. An appreciation for the limits on ice deformation rates downstream of larger obstacles highlighted a role for [...]
Reconstructing Aerosols Vertical Profiles with Aggregate Output Learning
Published: 2021-07-02
Subjects: Physical Sciences and Mathematics
Aerosol-cloud interactions constitute the largest source of uncertainty in assessments of anthropogenic climate change. This uncertainty arises in part from the inability to observe aerosol amounts at the cloud formation levels, and, more broadly, the vertical distribution of aerosols. Hence, we often have to settle for less informative two-dimensional proxies, i.e. vertically aggregated data. [...]
Subduction earthquakes controlled by incoming plate geometry: The 2020 M>7.5 Shumagin, Alaska, earthquake doublet
Published: 2021-07-01
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
In 2020, an earthquake doublet, a M7.8 on July 22nd and a M7.6 on October 19th, struck the Alaska-Aleutian subduction zone beneath the Shumagin Islands. This is the first documented earthquake doublet involving a megathrust event and a strike-slip event. The first event partially ruptured a seismic gap, which has not hosted large earthquakes since 1917, and the second event was unusual as it [...]
A CMIP6 ensemble for downscaled monthly climate normals over North America
Published: 2021-07-01
Subjects: Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics
Use of downscaled global climate model projections is expanding rapidly as climate change vulnerability assessments and adaptation planning become mainstream in many sectors. Many climate change impact analyses use climate model projections downscaled at very high spatial resolution (~1km) but very low temporal resolution (20- to 30-year normals). These applications have model selection [...]
Using sedimentological priors to improve 14C calibration of bioturbated sediment archives.
Published: 2021-06-30
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Probability, Statistics and Probability
Radiocarbon (14C) dating is often carried out upon multi-specimen samples sourced from bioturbated sediment archives, such as deep-sea sediment. These samples are inherently heterogeneous in age, but current 14C calibration techniques applied to such age heterogenous samples were originally developed for age homogeneous material. A lack of information about age heterogeneity leads to a systematic [...]
TEMPERATURE, SALINITY AND OXYGEN CLIMATOLOGY OF AFRICAN CONTINENTAL SHELF WATER, SOUTH OF THE EQUATOR, AND CHANGES SINCE 1945
Published: 2021-06-30
Subjects: Physical Sciences and Mathematics
The first temperature, salinity and oxygen climatologies for waters of the continuous southern African continental shelf is presented. It is based on oceanographic data collected since 1945, sub-sampled at depths of 5, 50 and 100 m on a mixed-spatial grid with 0.25° to 0.5° resolution. The climatologies capture spatial heterogeneities and seasonal variability in key ocean variables for the [...]
Interplay of seismic and a-seismic deformation during the 2020 sequence of Atacama, Chile.
Published: 2021-06-30
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
An earthquake sequence occurred in the Atacama region of Chile throughout September 2020. The sequence initiated by a mainshock of magnitude Mw6.9, followed 17 hours later by a Mw6.4 aftershock. The sequence lasted several weeks, during which more than a thousand events larger than Ml 1 occurred, including several larger earthquakes of magnitudes between 5.5 and 6.4. Using a dense network that [...]
The late Paleozoic paired metamorphic belt of southern Central Chile: Consequence of a near-trench thermal anomaly?
Published: 2021-06-30
Subjects: Physical Sciences and Mathematics
The hypothesis of a subduction-related Miyashiro-type paired metamorphic belt for the origin of the late Paleozoic igneous and metamorphic complex in the Andean Coastal Cordillera has remained unquestioned since its proposal in the early seventies. A synthesis of the advances in the study of these metamorphic rocks between 33°S and 42°S, revising field relations among geological units, and [...]
Paleoenvironmental change recorded in submarine fans: the Eocene-Oligocene climate transition in the Alpine foreland basin
Published: 2021-06-29
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Sedimentology
The Eocene-Oligocene transition (EOT) was a period of considerable environmental change, signifying the transition from Paleocene greenhouse to Oligocene icehouse conditions. Preservation of the sedimentary signal of such an environmental change is most likely in net-depositional environments, such as submarine fans, which are the terminal parts of sedimentary systems. Here, using sedimentary and [...]